1. Field of the Invention
The invention is related to the field of IMS networks and, in particular, to providing AoC services in IMS networks.
2. Statement of the Problem
Advice of Charging (AoC) is a service or feature in telecommunication networks that provides a subscriber with charging information for telecommunication services. The charging information may comprise a rate for a call (e.g., a charge per unit time, such as $0.10 per minute), a change in rate during a call, an accumulated usage or charge for a call just completed (e.g., call charge=4 minutes or $0.40), accumulated usage or charge for a billing period (e.g., total billing period=100 minutes or $10.00), remaining balance in an account (e.g., remaining balance=33 minutes), special charging, etc. The AoC service may provide the charging information to the subscriber at the start of a call, during a call, or at the end of a call. The AoC service may also provide the charging information in a variety of ways, such as through a visual display, a distinctive alert, an audible tone or announcement, or a combination of these.
To implement an AoC service, a switch in the telecommunication network determines the charging information that is available for presentation to the subscriber, and collects the charging information. For example, the switch typically includes a rate table that indicates the rate for a particular call (e.g., based on calling party number and called party number). The switch may perform this operation upon initiation of a call, during a call (mid-call), or at the end of a call. The switch then presents the charging information to the subscriber in a desired format, such as a visual display, distinctive alert, announcement, etc.
One type of communication network gaining popularity is an IP Multimedia Subsystem (IMS) network. As set forth in the 3rd Generation Partnership Project (3GPP or 3GPP2), IMS provides a common core network having a network architecture that allows for various types of access networks. The access network between a communication device and the IMS network may be a cellular network (e.g., CDMA or GSM), a WLAN (e.g., WiFi or WiMAX), an Ethernet network, or another type of wireless or wireline access network. The IMS architecture is initially defined by the 3GPP to provide multimedia services to communication devices over an Internet Protocol (IP) network, as IP networks have become the most cost savings bearer network to transmit video, voice, and data. Service providers are accepting this architecture in next generation network evolution.
One problem with IMS networks is that AoC services have not been effectively implemented. In traditional telecommunication networks (e.g., a PSTN, an ANSI-41 network, a UMTS/GSM network, etc), the switches provide the AoC services. However, traditional switches are not used in a packet-based IMS network as a serving network node, and thus AoC services cannot be provided by switches in an IMS network. It would be beneficial to both IMS subscribers and service providers that are using IMS networks to effectively implement AoC services in IMS networks.